/Engine/Source/Runtime/Engine/Classes/Particles/ParticleSystemComponent.h
Get the beam target tangent
true EmitterIndex and TargetIndex are valid - OutTangentPoint is valid false EmitterIndex or TargetIndex is invalid - OutTangentPoint is invalid
virtual bool GetBeamTargetTangent ( int32 EmitterIndex, int32 TargetIndex, FVector & OutTangentPoint ) const